Electrical storage battery



F. BOOTH July 28, 1953 Filed April .24, 195o I nbenio Attorney Patented July 28, 1.9543

`ELECTRICAL STORAGE BATTERY Frank Booth, Denton, near Manchester, England, assignor to Oldham & Son Limited, Denton, near Manchester, England, a British company Application AprilZl, 1950, Serial No. 157,701

` In Great Britain May 3, 1949 4 Claims. (Cl. 136--147l l, This invention relates to electrical storage batteries.

In the construction of storage batteries the positive plates are usually cast in grid form from an alloy of lead and antimony in which the lead predominates and the interstices are filled with the active paste of the various lead oxides.

To prevent metallic conduction between closely packed positive and negative plates by treeing in the negative plates, and to prevent short cir- 5 cuiting buckling, whilst permitting adequate electrolytic conduction between the plates, separators of sheet form of various kinds have been interposed.

Some separators are made from porous material such as thin sheets of balsa wood, or wood veneer or micro-porous rubber, whilst perforated separators are made from perforated hard rubber; the latter however are generally used with a micro-porous separator on the negative side.

To retain the active peroxide material in place on the positive plate, thin fibrous glass mats are commonly interposed between a micro-porous or a perforated separator, the libres of these retaining mats having a thickness` varying between .0002 and .0010 inch. the sheets of matted libres being of a thickness of about se inch. The lineness of the interstices of the mat is such as to eiectively retain particles of the active material fusing said coating material and to hold said mats firmly in position in contact with the active material of said plate. The material employed for the separator has considerable porosity and results in a high degree of electrolytic conduction.

The thermoplastic material employed is preferably polyvinyl chloride., Alternatively, the margnal areas of the sheet maybe coated with rubber and welded together by vulcanization.

The woven wrapping is preferably an open weave glass fibre material (l. e. l mm. to 6 mm. mesh), although other materials may-also be employed which providea substantially inextensible wrapping about the plate assembly. i The marginal edges of the sheet materialv from which they wrapping is made may be coated by treating only the edges, e. g, by dipping in sealing material, but preferably the Whole sheet is coated to facilitate welding of a flap passing under the electrode to the body of the wrapping as hereafter explained.

In order that the invention may be more clearlyunderstood, a preferredembodiment thereof in which the Wrapping is formed of open weave fibre glass material coated with a thermoplastic will'now be explained by way of example, reference beingY made to the accompanying drawing, in which:

Figure l is an elevation of the wrapping,

Without 1055 of Conductivity; 30 Figure 2 is a section on the line lI-II of Fig- The main object of the present invention is to urel, Construct 3, Separator which firmly holds the re- Figure 2a S, 2, View Slmlltli' t0 Flgllle 2 SllOWlllgr taining mats to the plate` before assemblyin 'the a modification in the construction of the S8199- battery, thereby preventing damage to the mats Tailor hereaftl referredtOi and during assembly, gives free conductivity of the 35 Figure 3 is a perspective-view 0f e battery Cut electrolyte, and provides for immediatev release of awa-y tolvshow the plates therein. bubbles of gas. IThe wrapping I2 is made up of open weave A further main Object is to improve the retainwoven glass material of. twostrand filaments ing properties of the standard type of glass fibre WOVBII at 20 courses per inch- The mesh Opening retainer mats and to provide a lpositive plate as- 4f, 0f the Wrapping l2 is then about l mm. square. sembiy in which the said retainer mats are se- The wrapping l2 is cut to suitably rectangular curely held in position in relation to the plate fOrm from a larger piece 0f material which has both before and after assembly in the battery. been @Called With polyvinyl Chloride and allowed A positive plate assembly for an electrical stort0 dryage battery constructed according to the present 45 The glass fabric retaining mais I3, I4 are placed invention is formed by applying a retainer mat to 0n the two faces of the positive plate l5 irl C011- each face of the positive plate, coating at least tact with the active material and the suitably the marginal edges of a suitably shaped sheet of shaped wrapping I2 wound tightly round the mats a substantially inextensible woven sheet material I3, I4 and plate I5 so as to hold the mats I3, I4 in inert to the acid of an electric battery with a 50 intimate relation with the active material. The thermoplastic material, tightly wrapping said edges of the wrapping l2 are overlapped and weldsheet across and about said retainer mats and ed together by the application of heat along the said positive plate so as closely to envelop said overlap I6; the polyvinyl chloride coating on the mats and said plate, and applying heat to said two laps fuse and so seal the edges together. marginal edges to weld said edges together by 56 Dropping of the active material from the plate 3. I is considerably delayed by the intimate contact between the mats I3, I4 and the plate |15.

In a modification, illustrated in Figure 2a, one side of the wrapping I2 is longer than the other as indicated by the reference I2a so that a flap is formed and after the vertical edges have been sealed together along the overlap I6, the ap I2a of the longer side is folded under plate I5 and on the wrapping and there secured in manner already described with reference to overlap I6, thus forming a bag in which plate I5 and mats I3, I4 are encompassed. Before being wrapped round plate I5, the wrapper I2 is provided with apertures to allow the usual lugs I8 to protrude from the bag.

Referring to Figure 3, the battery has the case I9, terminals 20, 2I and lling aperture 22. The positive plates I5 and the negative plates 23 are supported in the normal manner and each positive plate is provided with a Wrapper I2 enclosing retainer mats. Between the sides of the wrappers I2 and the adjacent negative plates are located micro-porous or perforated separators 24 of known kind to give necessary electrolyte space in the discharge and to prevent treeing In place of polyvinyl chloride, a coating of polyethylene may be applied to the wrapper I2, securing of the overlaps I6, being eiected by the application of heat as before. Again, the coating may be achieved by means of a solution of any thermoplastic material that can be brought into solution and that can be fused under heat and pressure, e. g. methyl methacrylate polymer in chloroform, or polystyrene in toluol or xylene.

The wrapping I2 according to this invention acts as a separator. It does not restrict the electrolyte conduction permitted by retaining mats I3, I4, firmly holds the latter in position and is easy to manufacture.

I claim:

1. A method of making a positive plate assembly for an electrical storage battery, which comprises the steps of applying a retainer mat to each face of a positive plate, coating at least the marginal edges of a suitably shaped sheet of a substantially inextensible woven sheet material inert to the acid of an electric battery with a thermoplastic material, tightly wrapping said sheet across and about said retainer mats and said positive plate so as closely to envelop said mats and said plate, and applying heat to said marginal edges to weld said edges together by fusing said coating material and to hold said mats rmly in position in contact with the active material of said plate.

2. A method of making a positive plate assembly as claimed in claim 1, in which the said thermoplastic material is polyvinyl chloride.

3. A method of making a positive plate assembly for an electrical storage battery, which comprises the steps of applying a retainer mat to each face of a positive plate, coating at least the marginal edges of a suitably shaped sheet of a substantially inextensible open Weave glass bre material with a thermoplastic material, tightly wrapping said sheet across and about said retainer mats and said positive plate so as closely to envelop said mats and said plate, and applying heat to said marginal edges to weld said edges together by fusing said coating material and to hold said mats rmly in position in contact with the active material of said plate.

4. A method of making a positive plate assembly for an electrical storage battery, which comprises the steps of applying a retainer mat to each face of a positive plate, coating at least the marginal edges of a suitably shaped sheet of a substantially inextensible woven sheet material inert to the acid of an electric battery with rubber, tightly wrapping said sheet across and about said retainer mats and said positive plate so as closely to envelop said mats and said plate, and vulcanising the rubber to weld said edges together and to hold said mats rmly in position in contact with the active material of said plate.

FRANK BOOTH.

References Cited in the flle of this patent UNITED STATES PATENTS Number Name Date 309,939 Faure Dec. 30, 1884 1,171,597 Davis Feb. 15, 1916 1,771,216 Gossler July 22, 1930 1,966,644 Pollock July 17, 1934 1,990,976 Booss Feb. 12, 1935 2,195,212 Hall Mar. 26, 1940 2,256,105 Shank Sept. 16, 1941 2,490,630 Jardine Dec. 6, 1949 2,504,608 White Apr. 18, 1950 FOREIGN PATENTS Number Country Date 2,073 Great Britain Jan. 24, 1884 of 1884 1,396 Great Britain Jan. 18, 1906 of 1906 347,012 Great Britain Apr. 23, 1931 751,398 France June 19, 1933 664,775 Great Britain Jan. 9, 1952 OTHER REFERENCES Gould: The Gould Unit-Seal Envelope, Railway Age, December 9, 1944. 

